In United States v. Freeman (9th Cir. 2007) 498 F.3d 893, a drug enforcement agent testified as both a lay witness and as an expert on the meaning of certain jargon known only to those with specialized knowledge of the drug trade. But the appellate court found the agent erroneously testified as an expert when he interpreted ambiguous statements not involving drug jargon, based only on his general knowledge of the investigation. (Id. at p. 902.) The court noted the difficulties that may arise when a witness testifies to lay observations and as an expert: the witness's aura of expertise may move the jury to grant the expert witness unmerited credibility when testifying about factual matters; a failed effort to impeach the witness as an expert may enhance the witness's credibility in testifying as a lay witness; an increased risk the expert will stray from reliable methodology and engage in sweeping conclusions, and the risk of juror confusion in discerning whether the expert is basing an opinion on reliable methodology or on personal knowledge of the case. (Id. at p. 903.) The Freeman court found "the line between the witness's lay and expert testimony was never articulated for the jury. This lack of clarity regarding the witness's dual roles created a risk that there was an imprimatur of scientific or technical validity to the entirety of his testimony." (Freeman, supra, 498 F.3d at p. 903.) Yet the Freeman court did not prohibit a witness from testifying in both capacities, and found a reduced risk of error if the jurors are aware of the witness's dual roles. (Id. at p. 904.)